A few more tips:
The arrival hall is a good / safe opportunity to:
1. Exchange USD or AUD to Sri Lankan rupees for a competitive price. After counting my money, I hand back one big note and ask them to change it to small denominations to start me off. (5000Rs will be hard to use in small places. 50Rs or 100Rs is useful for a small tip for someone in a toilet (handing you paper, turning on the tap) or for someone who loads your bag into a car. On that note: Men at the airport will try hard to confuse you into paying 1000Rs or more as a tip for the 10seconds it takes to put your bag in the boot. A simple no thanks, or if you weren't quick enough and your bag has been loaded, 100Rs would be plenty. The minimum daily wage is 400Rs.)
Side story: I once made the mistake of trying to change AUD500 at a street money changer, they literally had to send staff to another branch to fulfil my request, and after 45mins I had this wad of small notes so massive that people were staring in disbelief.
2. Get a pre-paid SIM at one of the booths. The SIM is free, and the attendant will tailor a plan for you. Last time I paid ~$10 for a month with calls and data. It can be topped up on the street if required.
3. Book your transport to the city or elsewhere. On the right hand side wall, there are pre-paid fixed price transport operators (private drivers). I have heard that the booth on the very right has Government Controlled pricing. There is more than one company to check prices with in the same location.
In Colombo:
1. Use a “Meter taxi” (tuk tuk) when in Colombo – just pay the fare on the meter, plus a small tip if the driver is nice. There will be annoying taxi 'pimps' at popular locations trying to 'help' you. You want a 'meter taxi' and nothing else - if the meter is 'broken' or they want to haggle on a price in advance, move on to another driver immediately.
By the way, if you find a nice driver don't hesitate to book him all day. Tell him where you want to go and agree on a rate for 4 hours or whatever. He'll be happy with the premium salary earned, and you'll have someone happily waiting to take you anywhere ... without dealing with hustlers trying to take you on a 'tour' for the day. You might even get some local knowledge. (You may be invited to his home to meet his kids and have a cup of tea, for me 'Unfortunately on this trip I'm just too busy. Thank-you and maybe next time.')
2. Don’t tip if you see ‘service tax’ on your bill, the tip has been included already. Otherwise I always tip when I feel like I’m getting a good price (as opposed to inflated tourist price) and someone has made an effort in their job. A few dollars to us goes a long way in Sri Lanka. And lets face it, if we are 'rich' enough to travel to their country, we can pay a bit more.
3. I liked visiting the shop 'Barefoot' which also has a lovely beer garden out the back. The prices aren't cheap, but the quality and range is an excellent example of the best of Sri Lanka.
Enjoy.